circulatory system pt.2

reactive hyperemia -

increase in blood flow to area where an occlusion has occurred

increased vasculature

- results from prolonged lack of oxygen/nutrients to an area (eg.

heart)

active (exercise) hyperemia

increased blood flow to muscles during heavy activity

a. decreased oxygen and increased lactic acid

b. visceral organ blood flow is decreased

Blood Flow to The Brain

MUST maintain constant blood flow (750 ml/min)

2. sensitive to low pH and high carbon dioxide

3. blood pressure tightly regulated in the brain

fainting

below 60 mm Hg

edema (brain swelling) -

above 180 mm Hg

intimately involved in temperature regulation pathway

increased body temperature ->

hypothalamic inhibition of vasomotor area ->

vasodilation of vessels in skin ->

increased blood flow ->

sweating -> (bradykinin -> more vasodilation)

Blood Flow to the Lungs

hort pathway from heart, less pressure required

low oxygen level --> vasoconstriction

Blood Flow to the Heart

blood to coronary arteries during diastole

2. vasodilation from ADP and carbon dioxide

diffusion

all molecules move DOWN the concentration gradient (from HIGH to LOW)

into or out of the blood

hydrostatic pressure

force from the capillary wall on the blood itself

filtration pressure -

the pressure forcing fluid and solutes through capillary clefts

osmotic pressure

force driving fluid in the direction of HIGHER solute concentration

movement out: Hydrostatic pressure > Osmotic difference

movement in : Hydrostatic pressure < Osmotic difference

normal fluid movement

1.5 ml/min in the entire body

circulatory shock

blood pressure gets so low that blood will not flow adequately

hypovolemic shock

circulatory shock resulting from loss of fluid (bleeding, diarrhea,

burn

hypovolemic shock effects

heart rate increases rapidly

general vasoconstriction of vessel

vascular shock

extreme vasodilation causes sudden drop in blood pressure

vascular shock effects

snake and spider bites with NE blockers

b. septicemia - bacterial infection

cardiogenic shock -

heart is unable to provide sufficient blood pressure